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Subject [jira] Commented: (GERONIMO-97) JCA - Connection Management
Date Mon, 06 Oct 2003 23:53:30 GMT
The following comment has been added to this issue:

     Author: David Jencks
    Created: Mon, 6 Oct 2003 6:51 PM
I've spent some time looking at the ConnectionManager part of this code, and I'm not very
happy with it.  I'm having a very hard time understanding how the classes fit together and
where any of the actual work occurs.

Two architectural decisions I disagree with are:
1. number of ConnectionManager instances.  I think it makes most sense to have a ConnectionManager
for each deployed ManagedConnectionFactory.
2. structure of interceptor stack for a ConnectionManager implementation.  If I understand
the design correctly, the interceptor class called Partition, and has multiple children. 
Each interceptor is responsible for deciding which child to delegate to.  While this is a
very powerful class model or meta-pattern, I don't think it is appropriate here.  IMO a ConnectionManager
for a single ManagedConnectionFactory/ConnectionFactory should have a single stack of interceptors
each of which can perform inverse operations for getting and returning a connection.  If an
interceptor cannot finish the request, it delegates to the single next interceptor, without
knowing what it is.

If I've misunderstood your design, please let me know.

I'm going to attach the preliminary implementation of interceptors I've been working on. 
My implementation is extremely incomplete (for instance it lacks a pooling interceptor) but
does include some transaction management and illustrates my idea for an interceptor implementation.

On another front, I think it is a good idea to deploy the ResourceAdapter and ManagedConnectionFactory
as mbeans so their properties are directly accessible via jmx.
View the issue:

Here is an overview of the issue:
        Key: GERONIMO-97
    Summary: JCA - Connection Management
       Type: New Feature

     Status: Assigned
   Priority: Major

 Time Spent: Unknown
  Remaining: Unknown

    Project: Apache Geronimo

   Assignee: David Jencks
   Reporter: Gianny DAMOUR

    Created: Thu, 2 Oct 2003 5:10 AM
    Updated: Mon, 6 Oct 2003 6:34 PM

This is the final proposal for the Connection Management section of the JCA specifications.
It is a "clean" version of GERONIMO-90 + a minimalist deployer which allows to test such an
implementation within a running server.

When I write "clean", it is evident that some works still need to be done, however based on
the size of the code-base - 30 classes - it should be great to reflect seriously on this proposal.

The content by package is:

The ConnectionManager spi interface has been implemented and delegates the allocation of connection
handles to a pool of ManagedConnection. By now, the ConnectionManager is really simple: it
delegates directly to the pool. However, one needs to hook-in the Transaction and Security
services in the allocateConnection method.

The specifications do not define how connection pooling should be implemented. However, some
non-prescriptive guidelines have been provided. One of them is to partition this pool. This
is basically what I have decided to implement: The pool is partition on a per-ManagedConnectionFactory
basis. By now, it is further partitioned on an idle, active, factory, destroy basis. The general
idea of this design is to define distinct set of behaviors depending on the kind of partition.

The factory partition is in charge of creating/allocating new connection handles. When its
allocateConnection method is called, it decides if a new ManagedConnection should be created
or if an existing one can be re-used. 
The XA partition (to be implemented) is in charge of creating/allocating new transacted connection
handles. When its allocateConnection is called, it enlists the ManagedConnection with our
TM and then gets a connection handle from this enlisted ManagedConnection. 

Inter-partition events can be propagated via an AWT like event model. This mechanism is used
for example by the factory partition: It monitors the idle and destroy partitions in order
to decide how to serve a new allocation request. More accurately, if a ManagedConnection is
added to the idle partition, then a permit to try a matchManagedConnection is added. If a
ManagedConnection is added to the destroy partition, then a permit to create a new ManagedConnection
is added. 

Partitions may be recycled. For instance, if a ManagedConnection seats idle too long time,
then this ManagedConnection may be eligible for recycling (destroy in the case of idle ManagedConnection).

The inner workings of ManagedConnectionFactory and ManagedConnection can be tracked via a
PrintWriter. LoggerFactory defines the contract to obtain a PrintWriter factory backed by
various output streams. 

A minimalist deployer for the outbound-resourceadapter nodes is implemented.


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